Is this Macro safe?

[Couch]

Quick question, I just wanted to make sure the new MAcro I just got is safe and will not spread to my display. I bought a 2 inch rock of fern grass as seen at saltwaterfish.com, and I bought 6 shaving brush'es. I think the shaving brushes are OK but what do you all think of this fern grass?

 

[mps9506]

I can't even tell what kind of macro algae that is from their photo.
Here is a link to the item if anyone wants to guess at what it is:
Fern Grass

 

[lcstorc]

My lfs has that sometimes. The seahorses like to hang on it and the turbos eat it. It never seemed to grow very much for me at all. I don't know of anything bad it will do and I have had it from time to time. It just gets gradually eaten in my tank. The tangs might eat it but I have never seen them eat it.